Im a fully insured motor mechanic. I was stoped in a customer car now facing charges for NO insuran

I was stopped using a customer car whilst I was out test driving. I am a full time motor mechanic and do 24hour call out service. Whilst driving the customers vehicle I was stopped about 100 meters from my trading address and was given a producer, I produced my documents and now recieved a summon stating that I do not have relevant use of insurance in place. The problem I have on his producer he stated I was using the vehicle for social and domestic use when I was using it in line of my business. The ower of vehicle was with me at the time and he has been co accused of letting me use a vehicle whilst being uninsured. Do I have a chance if I dispute as I already have 9 points and now am at risk of losing my licence. This is what I do for a living and if I lose my licence I will not be able to work as it will prevent me from driving to inspect customer vehicle for repairs.