How to fix my aircon on Renault 1999 Clio RXE?

I have a 1999 Renault clio RXE with 90,000Km on clock. Aircon became noisy and lost its cool, compressor was replaced and aircon topped up. Has been backwards and forwards 7 times with this recurring problem - is fine for a week and then starts making a noise again, noise stops when aircon switched off. Have now lost cool air again. What is wrong as aircon people can't seem to fix it? Thanks.