To add to the list of problems people have had with them (which I only realise the depth and frequency of their dodginess now by looking at forums after being ripped off myself) ....
@Goldcar 's customer service is awful! I hired a car for less than 40€ and @Goldcar have stolen 62€ by taking the deposit in GBP (having not allowed me to choose Euros) and returning it in Euros having skimmed 5%! I've tried to resolve x4 via 'customer service' (which itself is a nightmare!)
When taking the 'deposit' the Goldcar staff who dealt with me did not allow me to choose the local currency (EUR€) - he forced "Dynamic Currency Conversion" on me after I had entered my PIN - he stated the deposit amount in EUR€ - to change it out of sight is not acceptable and amounts to fraud - very annoyed as their customer service not helping after four tries.