Rain internet R250 Bad service vrs the R479 worst service

I have been with rain since August 2019 and had time where i was disconnected a couple of time without internet connection for almost 5 - 30 min. No problem it was until i have upgraded from R250 to R479 that my problem began. I cant watch any videos online properly without it buffering every 5 sec. I want to cancel my rain sim because whenever you send them a mail they keep on giving you a reference number tell you that someone will contact you but nobody does. No that i have cancel my sim today a email tell me that it will be disconnect on the 1 June next month. I dont want to cancel i just want you to downgarde me back to the R250 that has a faster speed.