My husband received a 'We have extended your PIP award' letter so in case this is of use or interest to anyone, they have extended the review due on 24/1/28 to .... 29/1/28. Yes 5 days difference!
Not sure it was worth them spending the time, printing and posting the letter for a difference of 5 days. It does also say 'We may extend the end date of your PIP award again. If we do so we will write to you and tell you about this'.