Refund Claim for Immigration Services

Approximately one year ago, I engaged the services of an immigration consultant with the objective of obtaining a UK Start-up Visa. During our initial consultations, they verbally assured me that, based on my profile, I would receive the visa approval within a timeframe of six months. Relying on this information, I entered into an agreement with them and paid a fee of £6000. The agreement explicitly states that the fee is non-refundable. However, it also mentions that if my UK Start-up Visa application were to be unsuccessful, they would assist me in exploring alternative immigration programs in other countries. Unfortunately, the agreement does not specify a timeframe for this provision. Regrettably, after waiting for a year & lots of follow-ups, I have recently been informed by the Consultant that my UK Start-up Visa application has failed due to changes in certain immigration laws. I am deeply dissatisfied with the services provided by them as they not only failed to deliver within the promised timeframe but also failed to fulfill their obligations, resulting in the failure of my case. Considering the circumstances, I am interested in pursuing a refund claim for the fee I paid to them. I seek your guidance on the best approach to assert my claim, despite the non-refundable clause mentioned in the agreement.