Can I get more than 20% discount from MedPlus?

Ordering about 2500 worth of specialized skin medications for a relative on medplusmart.com and bill comes to around 2500.

They auto applied 20% off and final comes to 2150.

There is a coupon box too. Any further reductions possible through coupon or payment mode?

I plan to use SBI CB card for further 5% off... does any other payment mode give more than 5% for this particular order?

* Ordering from MedPlus is fixed, alternative stores are not needed *

Thanks