Selling shares in Kraft Heinz

I am dealing with an estate that has a smallish holding of Kraft Heinz Common Shares worth about £4,000, which the executors are trying to sell. This is proving difficult and quotes we have received are suggesting the cost of getting a Medallion Stamp Guarantee and selling the shares is exceeding £1,000 which naturally the Executors are not keen on.
Has anyone had experience of selling these shares and possibly suggest a broker/ investment adviser who could help?
Any thoughts will be much appreciated. My direct email is