Solvent Weld leaking condensate pipe?

Looking for some advice. Last year I had my boiler replaced and it has been working fine for months. The condensate pipe takes a rather elongated route to the outside world and involves a number of angled joints. In the most recent cold spell, the pipe has started leaking at a number of the joins.

I reached out to the people who installed the boiler and had no reply (typical).

I did some exploratory investigation and found that the condensate pipe it just push fit together and with little effort can be pulled apart at the joints. Should the joints be solvent welded? Did my installers just forget this step?

If Solvent Weld will solve the issue, does anyone have any recommendations for what to buy?