hot water only in shower, mostly hot water in bathroom sink after plumbing job

my condo unit had a working bathroom shower and sink for about a year but recently it has got cold water only during weekends and shortly after that plumber seen outside apparently taking care of this issue.

However after weekends, I noticed shower has gone completely hot and bathroom sink will almost instantly turns hot as soon as I turn the faucet on. I get some lukewarm water after slightly turn on the faucet from off position but there is no way to get a cold water from shower at all.

I suspected something might have messed up and contacted hoa but they were insisting shower cartridge is the problem. That old lady at hoa management has been messing a lot with other resident's issues including mine in terms of handling so I can not quite believe her word. Needless to say, I have been pissed off several times with them as they have been dropping a ball /flip flopping a lot, when handling the resident's issues but that is another thing.

Next thing as I am planning to ask the neighbours which seems to be the best way to isolate the problem. However I am wondering based on this, what is likely the problem. It is possible that the cartridge can be problematic but just the fact that both shower and sink setting just suddenly went completely off the chart right after plumbing job after months of working seemlessly is for me smoking gun.

Check and make sure the toilet is getting cold water.
After that is would disconnect the suppy lines under the sink and make sure you are getting cold water there. Yoiu could get a pressur gauge to check the pressures from both supplies, might have to do some digging to find an adaptor for a gauge to work there.

there was a cold water definitely in the toilet. Also getting some lukewater on both. I knocked couple of neighbours and was able to get hold of at least one, she also said experienced the issue. She does not have a good mouth on HOA either.

I guess you need more people complaining.
With some old tub shower mixing valves,if the is no shower you could turn the valve to shower and stop the water and you would get some mixing.