Door handle bolts dont fit doors!

I bought several sets of brushed nickle door handle sets from Homebase for fitting to Premdor firecheck doors which are standard size and made of veneered chipboard. Quite good quality. The kit includes four threaded bolts for securing the handles through the door. They are too short!
The sets also include screws for optional screwing the handles on either side of the door.

The screws are very fine thread and unsuitable for holding in these doors. One handle has already pulled straight off and left damage.
I need longer bolts but these are made by the handle manufacturer and are not standard size. I have checked with my local fixture suppliers.
Homebase have never had another complaint about this which amazes me.

Am i the only one with this problem?

the allthreads or bolts are doubtless made to suit non-fire doors which are thinner

AFAIL if you email Homebase customer service with the part no/bar code off the handles, or else a good description, they will be able to contact the handle manufacturer.

I did that a while ago with some patio door locks, and they sent me a packet of spare keys free.

Can you post a pic with dimensions so we see what you mean?