Good afternoon, my name is ***** ***** I will assist with your query.
Most certainly a plumber, to find the fault. I take it you have tried to rod the drains and clear them with drain cleaner?
Its very unlikely you will need the pipes dug up, but if you do, plumbers generally dig up the pipes repair them then leave it for another trade to make good the surface (in your case floor). However if you have tried to rod the pipes clear and used drain cleaner, I would look to find a handy man or call a bathroom fitter.
Please let me know if I can be of any further assistance.
I havent heard back from you Alan,
Do you require any further assistance?