If you can somehow isolate the issue in the Mac portable to determine if it is either a hardware or software problem, then it may be a matter of returning to the shop who cleaned the Mac to see if some wires are loose to the wi-fi card on the logic board, or not. These can come loose on some models over their life, if the unit gets handled roughly, so that may be a possibility.
Did you set up a new Location to test the wireless connectivity? You could also make new Locations to test wi-fi at other sources if you happen into a coffee shop or such that offers 'free internet' but be careful due to other considerations, given the nature of an open or unsecure source, etc.
Another User account? Where you start the computer in a new user to see if there are any other possible conflicts within the one you've used most often, and also set up a new Location.
And be sure the computer saves your primary home as a preferred location, if it works out.
Not sure what else to check.
Sometimes wireless security methods or settings can be incorrect, or work OK for a windows machine but maybe not be right for the OS X version and settings in a later Mac system. WPA2? or better. And a base station may not supply the preferred signal frequency a newer computer may be set for, but should have support for an older one anyway.
Good luck & happy computing!
Wow, thank you so much...
First of all you are right I'll give it a try at the shop, although I think they'll charge me for just entering it
But what do you mean by setting up a new Location?
Thank you again for your help!!!
The main Location is Automatic if left unchanged in the Network preference panel.
If you click in it (automatic) that will allow you to Edit Locations. You can create new ones for testing purposes or for when traveling or for use in places where you may not want to change and save settings to a main Location such as your house or work wireless internet settings/set.
You can also choose to Create Network, or use Other network from the AirPort wireless icon menubar. If using a wired network such as Ethernet, the same main panel (network) can be used to set up alternative choices. All of mine are turned off except airport, but ethernet is a strong second when my Mac is near the wired internet router. I use ethernet to troubleshoot the wireless, too, on occasion.
These give you flexibility; just be sure you remember what you did, so you can change it back to what you were using, without having to choose 'reset to default' or generic fallback settings that may lose ones you already set.
Anyway, thought I'd say hi and add some words about this an than.
Good luck & happy computing!
Dear K Shaffer,
thank you so much for your insights! Well, you'll never guess what happened, I dropped my computer on the floor (from about 50cm height - not on purpose!) it seems something must have moved cause the problem stopped. I waited long enough to make sure it won't happen again, so now all good