Refusal to pay refund for error on vendor's side

Mid last year I signed up for a Portuguese course with EnglishAccess. Unfortunately I was sent the wrong course dates due to which I was not able to attend the course and asked for a refund which English Access promised to give me. <br> <br> Almost 6 (!) months and over 50 phone calls and many emails later, I have still not received the refund. A certain gentleman named Kai Drews (who supposedly looks after the accounts) promised me to transfer me the refund on 5 different occassions (in November, December, January and March) - however without actioning this. <br> <br> I simply do not know what to do anymore to get my money back. The extremely unprofessional manner in which this organisation is ran is just unbelievable and I advise anyone to refrain from taking any courses with English Access. <br> <br>