I am having problems with my bath and basin wastes. I bought new wastes for each, but cannot seem to get them to tighten up and seal properly to the bath and basin. They were admitedly cheap B and Q but they seem to leak between the new plughole and the bath/basin. They tighten up only so far and then just spin in place. Should I smother them in Plumbers Mate or go and buy better quality fittings. It also seems that the waste traps do not have a lot of thread with which to attach to the new plughole waste. Any help would be appreciated.
If they're spinning and not tightening up properly, then yes silicone or a jointing compound may work but probably only temporarily especially on the bath - as once you get in when it's full of water it may give eventually.
It's not necessarily because they're cheap - I've used Wickes and B&Q own brands before with no problem, it's possible that they've been overtightened and knackered the thread.
I would buy new ones (up to you what price you want to pay) Apply silicone to the waste grate where it meets the bath, then the underside of the bath use the seal/washers provided, make sure the bath and grate are clean and avoid over tightening.