I will try to assist you with this.
Although HMRC have a document called the Charter, UK Visas & Immigration don’t have a document with the same title, they do have a Customer Commitment schedule. In fact, the electronic title of the document is that it is a Charter.
The document is here:
Can I assist you any further with this?
Please rate the service positive. It is an important part of the process by which experts get paid.
We can still exchange emails if anything needs clarification.