State Bank Of India, Thrissur — Bank not crediting the refund.

I placed an order with Jiomart. Out of that order one item was out of stock. They issued a refund for Rs 259/-. The refund reference with the bank being[protected]. But SBI is not crediting the refund.They are saying they have not received any refund. Jiomart usually do not cheat customers. This is not the first time. Earlier also the bank had denied a refund later credited.The bank also not given me a refund of Rs.150/- from Flipkart.Such a big bank doing these small frauds? Pls look into this matter