Double billed and struggling to get my money back

On the 1st and 2nd of May 2015 I was double billed by Afrihost for my monthly ADSL bill. I've been with them for years and have not changed anything so I'm not sure why they double billed me now. I followed up within about 5 days when I happened to check my credit card transactions. Since then I have chased them many times. After the first few iterations they said it was my bank's fault. I went to FNB and it took about 24 hours to get written proof that it was not them. Since then I've been chasing and chasing Afrihost. They made me provide them with my credit card details 3 times (twice on the phone and once by email) and there is still no resolution. They've often promised to get back to me but have not honoured that - I'm the one who has to keep chasing them. This included a two-week period in the middle where they promised to get back to me - nothing happened until I chased them again. Latest feedback from them today is that they'll get back to me.<br> I generally like Afrihost and I do actually believe I'll get my money back in the end. But I must have spent at least 3 hours in total on this by now and I'm extremely frustrated.