You would be amazed at how many people think if your A/C doesn't work, you just have to top it up with refridgerant/freon. The freon should never need topping up unless there is a leak from a component, in which case the source of the leak should be repaired first. Not sure if it is the case here, but in the States, you can buy it in cans over the counter. People see the refilling connector, hook it up and the can explodes. There are two connectors - high pressure and low pressure. It's not like putting air in your tyres, and connecting to the wrong connector can be disasterous. Adding freon is not that easy and should be left to someone who knows what they are doing.