I was frustrated along with other drivers after dropping the cases off to go to park the car .The pay machine would not take the new pound coin and rejected this coin .I was fortunate to have an old one pound coin in my pocket which eventually allowed me to exit the area to park my car up.The car was securely parked and on our return from our holiday there was no issues with the bodywork etc.The only problem once again and this happens every time we do exit the car park.The machine would not accept the card to allow us to leave which caused tailbacks due to the fact we could not get through the barrier.We had to then contact the security to allow us to leave.In my opinion this needs to be addressed as it is quite frustrating coming off a long flight and been able to exit the car park due to the malfunction of the machines.