Worst Service from Call Centre

I really feel the lack of commitment and customer care from the call centre at Cell C is the worst. Last wednesday I contacted the Cell C store in Secunda. Ashley the consultant was very friendly and helped me to find a phone to which I can upgrade to. I advised Ashley that I am currently out of town and would come do my upgrade Friday. Friday I was at the store and my payment did not reflect which Ashley advised me I needed to wait till saturday which I did. Saterday came and Ashley advised me that he would not be able to assist me as I made a cash payment therefore I cannot upgrade. I have contacted customer care and they only reverted me to the upgrade department. The upgrade department only said that I am on legal status and therefore I could not be helped. This is the first that I heard about that as my phone is working and not off. My only concern is that 3 days ago they where prepared to do the upgrade and now all off a sudden the upgrade cannot be done. (bearing in mind that the last 2 payments I made was also cash). This is so stupid as I get penalised for paying their money. I have 4 contracts with them and 2 of which is bigger than the normal contracts. So I will have to wait for them to expire and go to a different service provider. For 2 years nobody had a problem with payments and all of a sudden no one at Cell C can assist me? I cannot understand this at all? All they are saying is "I understand your frustration". No, I do not think so.