Heating and Hot water set to heat, house up to temperature but hot water stone cold any ideas?

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Hi all, been a happy user of Tado for a few weeks, no issues other than EE4g router connection to begin with (sorted that).

Anyway we’ve had the smart schedule set to heat the HW for couple of hours in the morning and CH at the same time, never had any issues both with the old system or the Tado since bei my installed.

Today CH came on, HW on (shows on the app and on the programmer) house is now up to temperature, Wife gone to use the HW and its stone cold.

Not sure what’s gone on, as now the heating is maintaining temperature, only coming on occasionally, I’ve turned the HW on manually and it’s heating fine. Bit confused on that one, for info it’s oil heating system, HW tank upstairs (closed system) 2 zone valves one for HW one for CH.

Any suggestions, things to check would be appreciated.