Response times for requesting forms

My daughter has Asperger's Syndrome. She wants to claim benefits as she has not been able to work for fourteen months due to tendonitis in her forearms and wrists. She lives 130 miles away but, on a visit home at Christmas, we discussed her making a claim and I volunteered to phone the DWP on her behalf to request a form. She preferred to write to them to ask for a form. I posted her letter first class on January 6. She has not yet received the form. Is the DWP obliged to respond to such letters within a specific time? My husband also requested a form at the same time so that he and I could help her to complete it. His letter requesting a form was also posted first class on January 6. he has not received a claim form either.

She lives in Vale of White Horse District, Oxfordshire, so I don't know whether she can claim PIP but that's what she wants to claim.

She wants to claim PIP but I don't know if Universal Credit has been rolled out in her area. She is in a relationship so the last time she tried to claim any kind of benefits her boyfriend filled in the claim form for both of them. He works part time and they live with his parents. He works in Blenheim Palace so there is more work available at busy times. They got nothing at all for six weeks, one payment of £60, then his hours increased and the benefits were stopped. They both have Asperger's and found making a claim very stressful so we have been supporting our daughter financially now for two and a half years. She has absolutely no income of her own.

She has Asperger's Syndrome and is practically phobic about making or receiving calls. I will tell her that she must phone herself or allow someone else to phone for her. Thanks.