Sadly, yours is a common story with DLA applications. I had a similar experience with a claim for my daughter. Fortunately, I am a writer and researcher by trade and I took it upon myself to do my research and write a compelling appeal letter. 12 weeks later she was granted DLA at the highest rate and payments were backdated to the date of the original claim. Since then I have been helping others with their appeal letters through my business. We have been very successful with the appeals (6 out of 8 have had the decision changed) but unfortunately, I am not able to provide this service free of charge yet because it is a very lengthy process and takes time away from my other work, but I hope to do so in the not too distant future. You are absolutely entitled to DLA mobility and I recommend you stick with it and appeal. Research the Decision Makers Guide (this is the guide used to determine claims) and write a concise and detailed appeal letter providing any documentary evidence (doctors reports etc) to evidence that you meet the criteria from the DMG.