Community Matrimony — excess amount deducted

Excess amount was deducted from my bank a/c during an online transfer. It has exceeded 2 weeks since a refund of the difference amount was promised but no action has been taken so far. At first, they did not hold responsibility and blamed the nationalized bank through which i have been making transactions for decades. They also tried to convince me to go for a higher package for which they can adjust the difference in amount paid.