You think you have problems; I now have 50000+ emails in my inbox and cannot get rid of the repeating downloads. Every time i check my mail there is another 3/4000 repeats added to Outlook on both PC and Notebook and my iPad also has a similar change from read to unread and smartphone also adds another duplicate set to previous ones.
Reading the various Talktalk Community posts, it looks as though this is a Talktalk server problem which has now perpetuated for 2/3 months without meaninful solution or messages to subscribers to advise of the problem. Regretably I will also feel compelled to change ISP provider unless a satisfactory solution is advised very very quickly!
I have previously spent countless hours deleting stuff that even includes long previously deleted emails from 2013!! but it just keeps downloading again when i next check my emails from either device.