No I dont there is any restriction on making payments through credit cards. Today I paid both my Simpl and Lazy pay dues through my axis credit card.
In the case if Simpl, for transactions from 1st to 15th, the bill is generated on 15th and payment is to be made by 20th. Same way for next 15 days with due date on 5th of next month, beyond which there is a fine of Rs.10 per day. Works the same with Lazypay also.
So, assuming one makes a transaction on 1st of a month, he can get a credit period of 20 days plus 45 days on making payment through credit card. I have been using both Simpl and Lazypay for a very long now and have rarely defaulted.
Today I was surprised to receive an SMS from Lazypay asking to claim their Lazycard offering a credit limit upto 2 lakh. The card is a tieup with SBM Bank (India), which I found has received its banking license recently. It claims to have acceptance at almost all merchants (specially I could find e-commerce). So clearly, some sort of disruption is on the way