PIP Appeal Deadline and MP Complaint

I have been helping a friend with their MR. The friend contacted PIP twice after receiving their PIP renewal decision letter which saw a reduced award from enhanced DL to Standard. The points that were reduced were the same points that had been increased following a MR after their last review. The DM used reasoning that the claimant could drive and also that they could use a mobile phone and also that the claimant managed to open a tub of chewing gum and take a piece out while taking part in the video review. Alarmingly the DM stated that part of their decision was based on the fact that the customer was not currently under a consultant for Musculoskeletal or Mental Health conditions. PIP failed to send the HP Assessment report, so I submitted a MR based on what we had and also stated that the HP Assessment report was still needed and that further submissions might be made when the report could be studied. PIPwent on to make two telephone calls to the claimant asking questions about how her conditions affected her. During both calls the claimant again requested the HP Assessment report. The report was still not received and a MR decision was made to not change the award for the original decision. The claimant telephoned PIP and stated that she wanted to make a formal complaint and was told that they coudn't do this over the telephone and they would have to send a form out.
I made a formal complaint about PIPs actions in failing to provide the HP Assessment report and falsely stating that a complaint couldn't be made over the telephone to our MP. I alsoasked our MP to make the nature of the complaint known to Mims Davies, asking how PIP could be trusted to send HP Assessments reports to claimants before making a decision, when they cannot even do it when the have a legal duty to do it. I have received notification from the MP that they are going to take up the complaint with PIP. I have concerns now that a GE has been called and doubt if the MP will or can take the complaint forward. The claimant has since received the HP Assessment report and a letter stating that her complaint has been escalated, contary to what she was tpld on the telephone. My queation, the 28 day time limit to submit the appeal is fast approaching due to the postal delays and then actually receiving the much requested HP Assessment report. In my opinion the MR decision is not legal as the claimant was not provided with all the information that was needed to submit a compehensive MR request based on all the evidence that had been used in making the decision. The original decision was not that well worded and appeared to state that the DM had disagreed with the HP Assessment report. Now that I have had a quick look at the report the DM has just followed the points sugested in the report and probably meant that they disagreed with the previous award. Does the fact that PIP failed to provide the HP Assessment report and still made the MR decision without supplying the report and allowing for further submissions make the MR decision incorrect in law? Also if I wait for a result of the complaints, is that a reasonable enough excuse for submitting an appeal after the 28 day deadline. Many thanks in advance

Just a quick note to add that I have been contacted by the MPs office and they have confirmed that the MP will still be taking the complaint forward with PIP. I am in the process of completing the Appeal submission now. My friend would prefer a paper appeal as she suffers from situational anxiety in the form of Neurotic depression, reactive type. Are paper appeals less effective than oral ones as in success rates? Many thanks