2005 Vauxhall Zafira engine management light is on and the car won't acclerate beyond 20mph

Mine is a 1.8 Dual Fuel Factory fitted LGP/Petrol car. I recently got the LPG unit serviced at a local garage in Brimingham. Following the service the car engine started to revv without me pressing the throtle. Took the car back to the LPG garage and the guy there found a pipe which had come-off which he then glued with an adhesive. The car worked fine for like 10 miles and then the engine warning light started to show. Tried switching off and on the car but the light stayed on. Drove the car for another mile or so and then the the engine warning light went off and another engine managment light came on. After the car seem to gone in the Limp Mode and it does not accelarate beyond 20mph.

Car seems to be running OK on petrol and LPG

I am not sure what the LPG servcing guy did but the car is in a complete mess now.

What do i do now. Is are a problem with the LPG unit. Is it a problem with the ECU unit ?

Please help and advise where do I take this car to ?