It appears to be a glitch. The price for Royal Mail small parcel up to 2Kg and medium parcel up to 1Kg is actually supposed to be decreasing to £3.38 from next Tuesday:
'Starting 20 May, we’ll be introducing additional small parcel sizes and new competitive postage rates.'
For items sold between £0-100
| Item weight & size | Both couriers selected | EVRi only | Royal Mail only |
| 1kg large letter | £2.70 | £2.94 | £2.72 |
| 0-1kg small and medium parcel | £2.94 | £2.96 | £3.38 |
| 1-2kg small parcel | £3.38 | £4.06 | £3.38 |
| 1-2kg medium parcel | £3.71 | £4.06 | £5.15 |
| 2-10kg parcel | £5.21 | £5.64 | £6.65 |
| 10-20kg parcel | £7.19 | | £10.80 |
