If you have any flow at all, try two big loads of boiling water. After the first has passed, the grot will be softer, and the second, by the time it's heated, will do more clearing.
Mr Muscle does at least somtimes work.
So do drain unblockers cantaining sulphuric acid, but it's nasty stuff.
Are you saying that you have got a blockage, or poor flow down the drains?
Please describe what is hapening.
It might be poor design and build; it might be a colapse; it might be tealeaves/rice//bacon fat/kitchen roll/disposable nappy/plastic toy but you haven't given any clues as to what is happening and why you have had to make several attempts.
Bathroom basin is not so likely to have undesirable things pushed down it. Has it got a bottle trap? they are very prone to blocking for no apparent reason. Have you taken the trap off and emptied it?
Maybe you have a long horizontal run or something before it joins the stack; or maybe there is something horrible in the stack.
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