| Period | Surcharge p/kilo |
| 1st Feb - 30th Apr2008 | 16p |
| 1st May - 31st Jul 2008 | 21p |
| 1st Aug - 31st Oct 2008 | 27p |
| 1st Nov - 31st Jan 2009 | 14p |
| 1st Feb - 30th Apr 2009 | 9p |
| 1st May - 31st Jul 2009 | 10p |
| 1st Aug - 31st Oct 2009 | 12p |
| 1st Nov - 31st Jan 2010 | 16p |
| 1st Feb - 30th Apr 2010 | 16p |
| 1st May - 31st Jul 2010 | 16p |
| 1st Aug - 31st Oct 2010 | 17p |
| 1st Nov - 31st Nov 2010 | 18p |
| 1st Feb - 30th Apr 2011 | 23p |
| 1st May - 31st Jul 2011 | 30p |
| 1st Aug - 31st Oct 2011 | 28p |
| 1st Nov - 31st Jan 2012 | 27p |