MWEB FIBRE

Hi, I am furious I don't understand I have downgraded from a 20/2 to a 10/5 in August 2020 already (because for the 12 months I paid R614 and now all of a sudden Vumatel wants to put up the price to nearly R900), now my bill is send with an amount of R829 not R614. As far as I know i pay in advance. Meaning I pay then use. If I have giving notice in August I should not get a bill that is R829 it should be for R629. I am highly disappointing and if you not able to assist me I will then look for someone that would like my business. I am not interested in paying Vumatel their expensive asking rates and definitely not entertaining MWEB after all these years. I am your client treat me that way.