Agony Plant advised:
‘The compost looks very wet. This could be because your Mum is too generous with her watering, or the compost doesn’t drain well, or both.
If you can get a terracotta pot, slightly bigger than the one it’s in now that would be ideal, because the pot will evaporate water unlike a plastic one. Fill the gap between the rootball and the new pot with fresh compost – try to get a multi-purpose peat-free compost with added bark.
Put the pot on something to raise it slightly above the ground. Then start feeding with a liquid tomato feed, according to the instructions on the bottle, but don’t let the compost get saturated.
Tomatoes are tough plants so it should recover.’