Finding 'simple delivery' to be anything but. Can anyone help me set more useful postage options?

[surfingmelon04]

I have a listing for lengths of silicone rubber tubing here. 

Before 'simple delivery' I had a postage method of basically the cost of a stamp, as that dealt with small orders of 1m that fitted in an envelope, and larger ones where the few extra pounds in P&P could be recouped from the larger order.

I've just had an order for a few metres of the smallest tubing, which in old terms would be at most a large letter, depending on how good I was at coiling it flat to be below 0.5cm and fit in the normal letter size. However, eBay has charged the buyer £5.54. Even a tracked 24 large letter is only £3.35 as this stuff weighs very little.

I feel this 'simple delivery' is anything but. Perhaps there is a way to still adjust the postage cost within 'simple delivery' that I don't know about? If so, can anyone advise me on how best to arrange things such that people who buy 1m aren't wildly overcharged?

[style_wise]

Your listing shows £2.72 Simple Delivery charge, which is Royal Mail Large Letter Tracked 48 under 100g. This is the cheapest Royal Mail option, so you've listed the tubing correctly.

[papso22]

Did your buyer place two separate orders?

[surfingmelon04]

They placed a single order for 4m at £1.50/m. I have revised the listing this afternoon since my post as I discovered my 'variations' pictures had been deleted. When I was revising it, in the 'postage' section it said the minimum buyers would be charged was £3-something, so different again! The only change I have made to postage was opting out of the Global Shipping Programme, which I didn't realise was available until poring over the options today.