Noise in an Xantia

Hello, I tell you to ask you to help me with a problem that I have in the Xantia.

It turns out that I have detected a noise in the car and took it to the workshop. In the workshop they tell me that it is a problem of the circuit that goes the suspension and the brakes, they have to change a valve and clean the circuit with a liquid (4 liters) that are worth 160 euros (the liquid saying) and the 1000 kms again throw that liquid again, that is 800 euros. If it does not work, the same should be done in the back (300 euros).
Worst of all, it does not guarantee that it will look good. The COHE is 10 years old and 140,000 km.

My question is, if it is worth fixing it and if it will look good.

Thanks for the help. All the best

It all depends on the mechanic, it would have to look good because they would make a repair, if it is worth it, provided that the vehicle feels uncomfortable to handle or drive it if it gives you clear problems, but you handle it until it bursts and is already