The Ghana Revenue Authority says it has dealt with operational challenges that make the process of paying taxes cumbersome.In the recent past, some tax payers complained about the unavailability of tax certificates while others said the customer service at some GRA offices left much to be desired.But Commissioner General of the Ghana Revenue Authority, George Blankson says a lot has been done to improve the processes.On the availability and use of tax certificates, he said GRA officers have had to give them out with some degree of caution as some ill intended clients were using them for the wrong reason.