Company’s delay and refusal to refund my money

I had hired a digital media company to design a website. Half the amount was paid in advance while the second half was to be paid after the completion of the product. nThey had promised to complete the project in 3 months, but due to their internal inefficiency and shuffling the project took more than 5 months. At the end of the 5th month, they told me they could not deliver on the project and hence we mutually decided to terminate the project. nThey promised full refund. They took my account details and everythingnKeep in mind, just reaching to this verdict took 2 months of negotiating. nIt’s been more than a month since they promised the refund and I haven’t received it yet. nThey don’t respond or reply to my calls and messages. nWhat should I do?