sunbeam 3

Hi. After my E61(2004) has been in a garage for 5months;due to ongoing fault-the garages insurance company has agreed to pay the cost of new engine: I am finally getting the car back this week with a new enginge fitted (I have to pay 35% of the cost;about £3300.00 ).Has anybody any similar experiences of this;specifically what should be my primary concerns regarding the above?e.g.(1) has anybody ever been in negotiations with a garage's commercial insurance company;(2)is 35 % a reasonable contribution (3)I am claiming loss of earnings too;as this car is my sole business,I have had to rent a vehicle for business at a cost of £145.00 per week...Any comments would be be most appreciated,thanks