Infinia - High value transaction getting declined

I am trying to part pay (15L) for a car using Infinia. My limit is higher than that. Tried swiping for Rs1 to check MCC and it went through. Next tried to swipe for 15L and it got declined with RR_035 error code saying declined due to risk. The pos is PayTM machine. Called Infinia customer care and they were clueless. After some time tried for 5L and it went through. Got automated call from transaction monitoring and approved it as well. Again tried 5L and it failed. Customer care asked to try smaller amount. Tried 2L+2L next and after that again it got declined. I wasted full day today waiting in-between transactions, calling customer care etc. Customer care is saying they saw only the successful transactions and nothing got denied from their end.

I still have 6L remaining to pay which I will try tomorrow. Any tips on how to make such high value transaction in Infinia.