Pipes leaking

Hi all, I’m looking for some advice on a leaking issue we’ve been having.

So last year we had a leak coming from our living room ceiling. Took some of the ceiling out and found some quite bad mould. There was a lot of dampness and water build up. Noticed a leak from one of nuts at the elbow joint of the pipe. Called a plumber and he came out and just tightened the nut and said it’s wear and tear. It is an old house. So got a plasterer in to fill in new plasterboard etc. Thought job done.

About a month ago we had another leak in another part of the living room ceiling. Tore part of it down and spotted water dripping again from a nut on one of the pipes. Called out same plumber and again all he did was just tighten the nut and again put it down to wear and tear. Old pipes he said. So dried it out, plastered it up, painted ceiling etc.

So now we have a leak coming from the kitchen ceiling. I’ve cut off part of it and again notice water coming out of a nut at the corner joint of the pipe.

At this stage, I’m not calling the same plumber. Surely as this stage three separate leaks from three separate pipes is a major issue. I don’t think we can keep putting it down to wear and tear. Has anyone any advice on the next step?