Refund not received

On December 11th I wanted to use this application to send money to another bank account, I couldn't make any transfers because it rejected them but it did take the money I tried to send, I asked to cancel the transactions because the app took the money twice and did not return it, now every time I talk to customer service they say that they are solving a technical failure and they will keep me informed, but it's been almost a month and I haven't received a response