It is possible to get the TAM (formally HRAM) system to ignore a clocking, but not to delete it completely, the only clocking that can be deleted is one that’s been entered manually. This was the same on HRAM so nothing has changed in that respect.
As far as being on holiday and working OT, this can be arranged through moving the scheduled hours for the holiday to a different time/day and then placing an additional shift on, but clumsy but still possible.
The W&P system is no worse than any of the previous payroll systems that we’ve used, it all comes down to the person inputting the correct information, by clicking correctly you protect yourselves by having supporting evidence if you think your wage is wrong