Immersion on 5 hour nightsaver - no hot water by evening

erratic

I'm in a rented apartment.
There was a Grasslin immersion timer switch until it stopped working a few weeks ago.
This was set in 15 minute intervals for 2 hours overnight, and 1 hour in the evening. There was ample hot water, probably could have reduced the times.

It was replaced with a new Horstman E7, which comes on for 5 hours (no other option) overnight, and has a boost of up to 2 hours. This was fitted by the estate agents electrician. With either the timer or boost on, you can hear an element heating.
switch.jpg

One 10 minute shower is taken in the morning. The pipe leaving the tank feels hot 20 minutes later. No one is in the apartment during the day. By evening the water in the hot tap is cold. There are no obvious leaks or dripping taps that I'm aware of. It takes over an hour to heat enough water for a shower in the evening. I'm told by the estate agent that this is normal.

The cylinder seems well insulated.
cylinder.jpg
Both elements are marked as 2.75/3.0KW
The thermostats do not have temperatures marked, just a range from + to -. They are both set at the plus end of the scale.
thermostat.jpg

Any suggestions?

M cebee

possible he's swapped the top and bottom elements by mistake

should work fine assuming elements are in good nick and there's no leaks