Downloads speeds issues

[WildBill]

Since I got my broadband the downloads speeds vary from 37 to 74 with a guarantee of minimum of 50

would anyone like to advise me what is causing my problems and can it be solved.

i get constant buffering and picture locks.

[WildBill]

This has only happened since when I got broadband fibre fitted,no issues as serious as this when I had viper cable to property