Club Mahindra Holidays — Retrospective tax added on EMI

My membership id is 2559930. I have completed all my EMI dues in 2018. Today while paying for the Annual Subscription Fee, I saw that they have charged me Rs. 9798.5 as past tax dues.
How can Club Mahindra ask for retrospective tax for payment done in 2018 from me? This is just unacceptable!
In order to pay the Annual Subscription Fee, I had no option but to pay these past tax dues since the ASF couldn't be paid without the tax dues. Please look in this matter as soon as possible and kindly help me to reverse the past tax dues.