Creditors can just as quickly delete tradelines (TLs) as they can add them. Assuming Midland owns the debt / authorized to collect, they're giving you the run-around. Midland simply needs to delete the TL, and the issue is solved. Some debt collectors will suggest disputing with the credit reporting agencies (CRAs) to avoid updating the TL themselves, which costs money...
Also, some debt collectors don't want consumers to know how easy it is for TLs to be deleted; don't want to acknowledge how shoddy their collection / record-keeping practices really are.
Midland is bad news, and am so glad their TLs are finally falling off my reports. You mention disputing since 2014, but how old is the original debt? If it's early 2009 or older, easiest approach is simply wait several months for the TL to fall off your reports.
On a related note, be aware when applying for a mortgage that other creditors / debt collectors can detect such activity. Can result in debt collectors coming out of the woodwork; less agreeable to negotiating discounted settlement nor PFD, since they know how important "clean" reports are for getting favorable mortgage rates / terms.
Focus on Midland to get it deleted - they added it, they can delete it An intent to sue letter and/or BBB complaint might do the trick - read other posts for other approaches. Personally, I'd suggest be the squeaky wheel - call Midland every day and send many letters insisting they follow-through on their settlement agreement to delete the TL.
