The fault has already been diagnosed - it lost 70g of coolant in a week.

If the syustem is refilled up to full pressure, then the loss rate will be higher (think of any system under pressure with a leak. The higher the pressure, the greater the leak).

So you need to find out where the leak is coming from, and get that fixed.

One issue that often comes up is not a 'reliability' one, but of operation of the system. Most car owners rarely read the A/C section in the handbook as they think they are so easy to use.

This is true in most respects, but what they forget to do, especially with little used cars, or those living in areas/countries that a good portion of the year doesn't require the cooling function of the A/C, is to run the A/C or heater component to keep the system in tip-top condition:

1. In winter, at least once a month, if not once a fortnight, run the cooling for 10-15 mins so that the cooling system actually runs the A/C system, not just uses outside air to 'cool' the car (whether its needed or not). This may mean you have to turn the temperature setting to its minimum setting to get it to run in that mode.

This is to ensure the oils in the system circulate, lubricating the components and making sure they and the joints/seals don't dry out. Not doing so will eventually knacker those components (a bit like starting a rarey used car and thrashing it straight away, before the engine oil has had the chance to fully circulate) and can lead to leaks via the dried up seals.

2. Additionally, the heater should be used for the same time once a month or two normally, as often as required - on max temperature and recirc with a decent airflow rate (on manual control) to all vents (change as required), to kill off any accumulated bacteria in the air ducts. If the air from the system smells musty (especially when its not damp outside), then it needs doing, as that's the bacteria and moisture causing the smell. Using the cooling function of the A/C will only make it worse. Not doing so can lead to occupants getting more regular respiratory illnesses or make them worse/longer lasting.

Both these 'easy win' techniques may be a bit uncomfortable given you want to use the opposite in the weather at the time of year, but are well worth doing to avoid big bills for new A/C systems (recharging won't always work for the first) or being ill more often.

Whilst the above won't help the OP now, it could be (not necessarily) the reason (first issue above) why it happened, and is worthwhile doing for the future to avoid the problems I mentioned.

shame .my view is once its broke ,you just keeping throwing money at it . to no avail. sorry just my opinion