KEDU PD20B 220-250V 10mA 16A RCD Trip for Lay-Z-Spa with moulded plug These are the same as the PD22B but have larger reset test buttons which are rubber. These are all pre owned units and have been removed from pumps but have all been tested.
I was praying that this was the fault to Lazy spa as otherwise it could have cost a lot more
The Switch breaker was as described and solve my problem.
Would recommend this