ROAMING CHARGES

I have been with Cell C for the past 11 years and can say I have not had a problem until this year, I went overseas for 10 days in December 15 and received a GPRS bill of R2k in Jan 16 and then another R3k in Feb 16, I have requested a few times for details of these charges and received an sms saying I must switch certain things off on my phone and that the data charges on the bill are correct. They state in the sms that I can have the IP addresses of the hugh amounts I was charged on but still have not received same. The charges for the Feb 16 bill were all on the 31st Dec 15 whilst I was at Heathrow Airport (wifi!!!!) and then to top things off I was charged R125 for a data roaming call on the 31st Dec which I know for a fact I did not place, I did call this number when I landed back in SA on 1 Jan 16 from my kitchen, this person is also cell c and lives maximum 5km away from me!!!! They have taken my money by debit order but have still cut off my international dialing (my son lives in the UK). I have been overseas previous to this visit, with the same phone and never received such a high account, my son has wifi at his home and the airport also has wifi, really fed up!!!