Refund of iverpayment for Parking Space

The company I work for used Servest parking services and in November 2018 the contract came to an end. As they rarely sent me any invoices/statements i always automatically paid on the 1st working day of the month and did so in December 2018. At the end of December I got an invoice from the new company which i paid assuming that it would be for January. I was sent a statement from the new company saying i was month behind and upon investigation i found out that i paid Servest for an extra month. I contacted them and was sent a form to fill in so that they could refund the money. I have sent numerous emails, tried to call them and even sent a please contact me on their website and still nothing.

They are quick to block access to the parking for late payment but not as quick in refunding or replying to queries