Tap Carpets- £300 extra costs?

[CarrotSide123]

Went into Tapi Carpets today and ordered a Stair carpet. It was on sale, £66.per m sq down to £32.99 per m sq. Its for our stairs and a small landing at the top.

Our price to pay was £826. We got an Underlay which was £15.99 per sq m.

This is before fitting, which is roughly £150.
Online calculators have put my carpet costs (according to my measurements) as £360.58, Underlay £174.77 which leaves about £330 left over. I have found online that Tapi charge a £40 delivery, but what else would then cost £290?? We need carpet rods and 1 threshold, which are included.
A Tapi chap is coming out on Saturday to measure prior to the fitting, but I am intrigued if anyone on here can help me before then as I am curious.

Doesn’t the extra money account for the carpet rods and threshold?
Stair rods aren’t an insignificant cost. They also won’t be pricing for the exact dimensions as there will need to be some tolerance built in.

I'll bet the fitting is more than £150,these firms with amazing deals can be sneaky AF.
Watching with interest op.

It’s because you don’t just pay for your measurements. So if your room was 4.2 metres wide the carpet come off a 5m wide roll

Ive asked for a cost breakdown.
The carpet we ordered comes in a 2.5m roll, Im wondering if they would use the 2.5m or 4m ?
Only 1 threshold required.
Lots of carpet gripppers would be required but these are not that expensive.

Just looking on their website the threshold we ordered was £12.99.

2.5 m surely for a stair carpet.

I have received my quote breakdown, they've charged the carpet as 4 meters at and 14 m sq required.
The pre measure person is coming on Saturday, so I will ask about the 2.5 meter roll.