Airtel - Airtel service refuse to help wrong recharge done

I'm a user of a prepaid mobile number since ** years. Two days ago I recharged my phone with a plan using a third party app - Payzapp. I intended to recharge with a year-long unlimited calling plan but accidentally recharged with an international roaming plan. The international roaming plan activated when I land in a different country. I have no requirement for this and I called the Airtel customer service to help me. They refused to help me and hung up on me twice. I wasn't even asking for a refund, I'm asking them to change the recharge plan to a different one of the same amount but they refuse to help.