diff --git a/library/src/calculate_price.cpp b/library/src/calculate_price.cpp
index c3ac388..5845a27 100644
--- a/library/src/calculate_price.cpp
+++ b/library/src/calculate_price.cpp
@@ -14,12 +14,14 @@ QList<int> CALCULATE_LIBRARY_API get_time_steps(Configuration *cfg) {
     return Calculator::GetInstance().GetTimeSteps(cfg);
 }
 
-int CALCULATE_LIBRARY_API get_minimal_parkingtime(Configuration *cfg, PERMIT_TYPE permitType) {
+int CALCULATE_LIBRARY_API get_minimal_parkingtime(Configuration *cfg,
+                                                  PERMIT_TYPE permitType,
+                                                  int paymentOptionIndex) {
     int minTime = 0;
 
     switch(permitType) {
     case PERMIT_TYPE::SHORT_TERM_PARKING: { // e.g. szeged (customer_281)
-        minTime = cfg->getPaymentOptions().pop_min_time;
+        minTime = cfg->getPaymentOptions(paymentOptionIndex).pop_min_time;
     } break;
     case PERMIT_TYPE::DAY_TICKET_ADULT: {
     } break;
@@ -30,20 +32,22 @@ int CALCULATE_LIBRARY_API get_minimal_parkingtime(Configuration *cfg, PERMIT_TYP
     default:
         // for each new sell-procedure, recomute the timesteps. implicitly, set
         // the minimal parking time.
-        Calculator::GetInstance().ResetTimeSteps();
-        Calculator::GetInstance().GetTimeSteps(cfg);
-        minTime = qRound(cfg->getPaymentOptions().pop_min_time);
+        Calculator::GetInstance().ResetTimeSteps(paymentOptionIndex);
+        Calculator::GetInstance().GetTimeSteps(cfg, paymentOptionIndex);
+        minTime = qRound(cfg->getPaymentOptions(paymentOptionIndex).pop_min_time);
     }
 
     return minTime;
 }
 
-int CALCULATE_LIBRARY_API get_maximal_parkingtime(Configuration *cfg, PERMIT_TYPE permitType) {
+int CALCULATE_LIBRARY_API get_maximal_parkingtime(Configuration *cfg,
+                                                  PERMIT_TYPE permitType,
+                                                  int paymentOptionIndex) {
     int maxTime = 0;
 
     switch(permitType) {
     case PERMIT_TYPE::SHORT_TERM_PARKING: { // e.g. szeged (customer_281)
-        maxTime = cfg->getPaymentOptions().pop_max_time;
+        maxTime = cfg->getPaymentOptions(paymentOptionIndex).pop_max_time;
     } break;
     case PERMIT_TYPE::DAY_TICKET_ADULT: {
     } break;
@@ -57,12 +61,14 @@ int CALCULATE_LIBRARY_API get_maximal_parkingtime(Configuration *cfg, PERMIT_TYP
     return maxTime;
 }
 
-int CALCULATE_LIBRARY_API get_minimal_parkingprice(Configuration *cfg, PERMIT_TYPE permitType) {
+int CALCULATE_LIBRARY_API get_minimal_parkingprice(Configuration *cfg,
+                                                   PERMIT_TYPE permitType,
+                                                   int paymentOptionIndex) {
     int minPrice = -1;
 
     switch(permitType) {
     case PERMIT_TYPE::SHORT_TERM_PARKING: { // e.g. szeged (customer_281)
-        minPrice = cfg->getPaymentOptions().pop_min_price;
+        minPrice = cfg->getPaymentOptions(paymentOptionIndex).pop_min_price;
     } break;
     case PERMIT_TYPE::DAY_TICKET_ADULT: {
     } break;
@@ -119,7 +125,9 @@ int CALCULATE_LIBRARY_API compute_product_price(Configuration const *cfg, PERMIT
     return 0;
 }
 
-int CALCULATE_LIBRARY_API get_maximal_parkingprice(Configuration *cfg, PERMIT_TYPE permitType) {
+int CALCULATE_LIBRARY_API get_maximal_parkingprice(Configuration *cfg,
+                                                   PERMIT_TYPE permitType,
+                                                   int paymentOptionIndex) {
     int maxPrice = -1;
     static const PaymentMethod paymentMethodId = Utilities::getPaymentMethodId(cfg);
 
@@ -128,8 +136,8 @@ int CALCULATE_LIBRARY_API get_maximal_parkingprice(Configuration *cfg, PERMIT_TY
         if (paymentMethodId == PaymentMethod::Progressive || paymentMethodId == PaymentMethod::Steps) {
             maxPrice = Utilities::getMaximalParkingPrice(cfg, paymentMethodId);
         } else { // PaymentMethod::Linear -> e.g. szeged
-            int const key = cfg->getPaymentOptions().pop_id;
-            int const maxTime = cfg->getPaymentOptions().pop_max_time; // maxTime is given in minutes
+            int const key = cfg->getPaymentOptions(paymentOptionIndex).pop_id;
+            int const maxTime = cfg->getPaymentOptions(paymentOptionIndex).pop_max_time; // maxTime is given in minutes
             std::optional<QVector<ATBPaymentRate>> const &pv = cfg->getPaymentRateForKey(key);
             if (pv) {
                 QVector<ATBPaymentRate> const &paymentRate = pv.value();