PIP MR evidence gone missing should I comnplain?

Hi, I need help please.

After spending 6 weeks putting together a 40 page document for my MR including new GP evidence it has gone missing.
I had called DWP to confirm an extension until 6/4/18 and the document was delivered and signed for by DWP on 6/4/18 so it was on time. I then received a letter dated 6/4/18 saying because my evidence was late the MR had been done without it.
I called DWP on 17/4/18 to ask and they said the evidence wasn't on the system and hadn't been scanned in. I spoke to a member of the MR team and they said they didn't know where it was. They said they would track it down and call back by the end of the week. They didn't call back.
I called again on 23/4/18 to be told I couldn't speak to the person I spoke to before and the evidence still wasn't on the system. They said someone would call me back. After saying I had already been waiting a week and I'm running out of appeal time she "looked again" on the screen and said there was an email saying it had been found and someone would call me back, it would be logged as urgent.

I am going to send in my appeal form anyway but do I have grounds to complain to the DWP?
Is there a data protection issue if they have lost the document?
Do they have to do the MR again if the evidence was ignored?

I have also contacted my MP.

Thanks.

They shouldn’t give people a deadline date if they are not going to stick to it. If it takes 3 days to get to the right department that should be built into their timescales. I don’t think saying it’s my own fault is very helpful to be honest.

It hasn’t been confirmed yet that it has been found, it hasn’t been scanned onto the system, I have been told that if they lost the documents I should complain because it contains sensitive health information.

I hope the complaint will maybe get the system changed ! If everyone complained when things were “lost” they might not be able to get away with it. If people complain when things are sent on time but ignored maybe they would build the time it takes to get to the right department into the system.

I hope the complaint would mean the MR would need to be carried out again.

How can they be allowed to ignore evidence and not carry out a new MR? Surely that warrants a complaint too.