Change of class:
Salwick-Stranraer route Dumfries SVH £32.60 (I'm assuming here that the SVH can be excess to as the is a single in the other direction in the same transaction)
SVH tickets are
ONLY sold through the Virgin Trains website as part of a return journey, generally involving an Advance ticket in the opposite direction. They're not available from Ticket Offices or on train.
By my reckoning, using the rules as currently printed in The Manual:
For the overdistance from Stranraer to Troon, I'd sell a new Anytime Day Single at a cost of £14.25 with Railcard discount, as this is less than the excess fare would be (now stated as the
FULL difference in Return fares).
For reference, the excess would be calculated as:
Y-P SVR Salwick - Stranraer rte Dumfries : £59.55
Y-P SVR Salwick - Troon rte Dumfries : £42.20
Difference : £17.35
For the change of route, ignoring the Stranraer - Troon leg:
Y-P SVR Salwick - Troon rte Carlisle : £48.05
Y-P SVR Salwick - Troon rte Dumfries : £42.20
Difference : £5.85
The amount charged for the excess could be any of £2.90, £2.93 or £2.95. I'd lean towards the former, as it's fairer to the passenger.
For the excess to First Class, again ignoring the Stranraer - Troon leg:
Y-P SOS Salwick - Troon rte Carlisle : £42.55
FOS Troon - Salwick rte Carlisle : £143.00
Sub-Total : £185.55
LESS Y-P SVR Salwick - Troon rte Carlisle : £48.05
Excess : £137.00
Giving a total to pay of £14.25 + £2.90 + £137.00 = £154.15
Though it could also be argued that you could do the whole thing in one step, which'd give the following:
Y-P SOS Salwick - Troon rte Dumfries : £37.30
FOS Stranraer - Salwick rte Carlisle : £161.50
Sub-Total : £198.80
LESS Y-P SVR Salwick - Troon rte Dumfries : £42.20
Excess : £156.60
Cheers,
Barry