Is my car okay? 2011 Suzuki Swift

I have a Suzuki Swift which I have had since 2018. I don't drive it much with only 55k miles, mostly motorway and A-roads in the past 2 years. Recently it has been requiring costly repairs since last year and the most recent MOT and service. Last year it was the suspension ball joints causing a MOT fail. This combined with other repairs totals at £580. Now there are advisories for the Rear shocks and a slight leak of the gearbox. Already spent £600 I would not be surprised if the costs will total £1000. Seriously considering selling and replacing it as I worry about what's to come next year, but car prices are fucked and I will be able to afford something worse at least not until I can get a proper full-time job which are non-existent. I thought Japanese cars like Suzuki rank highly in reliability

Also, how do you stop brakes from rusting and pitting from infrequent use? I only replaced them 3 years ago.