Thank you for your question
My name is ***** ***** I shall do my best to help you.
The executors of the Will had no right to withhold payment whatsoever and they are personally liable to you for the amount involved
You have not said who the Executors were - but if it was your Uncle and your mother then you need to write a calm but formal letter to your Uncle with a copy of the Will and asking for a copy of the final accounts.
Point out that he is personally liable to you for the unpaid amount and that you look forward ti his proposals, failing which you will take Court Action against him
Please ask if you need further details