have you yet checked the line using a corded phone?
Then you will need to get one, only about a fiver from the usual sources, invaluable as a diagnostic tool.
you can get engineer visit but if the problemis in your home - your side of test socket - then you will get billed for the engineer call out investing £5 in a corded phone will determine if your problem or openreach it is always there in case problem recurs
borrowed a friends spare phone and no sound inbetween
im guessing no problems my side
i know im not going to get anywhere near 67mb but im not even at the minimum 27mb with the max being 40ish
its between 10-20mb these days depending time of day
Then you need to phone 151 and get engineer visit. You will need to be insistent