My parents have lived in Brussels for the past 9 years, the first 5 of which I was living there too, and they spent a few years there way back before I was born. Despite this my Mum still can't speak French properly and whenever I'm home and helping out with chores I'm constantly having to jump in and save us from public embarrassment as she stares wide-eyed and dumbstruck at whoever's talking to her (for instance I had to explain to here that the coordinator at the dump wanted her to reverse the car a bit, despite his hand gestures making as much obvious).
That's not what grinds my gears - for the most part you can get by in this city with English and the most rudimentary French and she has my Dad to deal with any tricky French when necessary.
What pisses me off no end is that, despite this, she uses various unnecessary French words in conversation (I'm not talking about adopted phrases like your deja-vus and your faux pas - she calls the utility room a "buanderie" and keeps referring to the aforementioned dump as a "decheterie" for example) as though she's such a natural francophone she's somehow forgotten how to speak her own language... Pull the other one love.
Rant over.