All Clear act as Insurance Brokers for clients who require travel insurance covering pre-existing medical conditions. Obviously premiums are expensive due to the higher risk that claims will be made under the policy.
Not knowing who the actual Insurer/Underwriter was, we cannot check the policy documents, but I would think, from personal experience, that your claim will have been reduced by the policy excesses in respect of both the travel and accommodation elements of the holiday, e.g. two excess amounts not one. I would suggest that you re-read the policy documents to confirm if this is the case, then calculate what the refund should have been. The payment should have been accompanied with a covering advise showing the calculations, no matter whether it came from All Clear or the insurer/underwriter. If the figures don't agree, submit a complaint to All Clear using their official complaints procedure.