Can you show evidence? If so, simply reduce your donation by 0.1% and you'll be quids in.
Evidance is simply math, ok here it is, data from my transaction history page:
588272 2013-05-03 19:07:57 Debit_ATP 6eLKyhhfcZaQSZgCckCBGPHTM9gM9JL6HX -4.90047498
588071 2013-05-03 19:07:27 Credit 30061 0.239512
587002 2013-05-03 19:00:45 Credit 30057 0.237694
586054 2013-05-03 18:59:28 Credit 30031 0.25074500
585109 2013-05-03 18:59:22 Credit 30036 0.25163700
584150 2013-05-03 18:59:14 Credit 30037 0.25034400
583189 2013-05-03 18:59:00 Credit 30038 0.25103199
582225 2013-05-03 18:58:36 Credit 30040 0.25023800
581172 2013-05-03 18:52:46 Credit 30053 0.244045
580205 2013-05-03 18:52:40 Credit 30052 0.247816
579232 2013-05-03 18:52:34 Credit 30051 0.251162
578263 2013-05-03 18:52:14 Credit 30050 0.2513
577276 2013-05-03 18:42:40 Credit 30041 0.26005299
576267 2013-05-03 18:19:07 Credit 30017 0.262682
575323 2013-05-03 18:18:31 Credit 30016 0.267665
574359 2013-05-03 18:14:38 Credit 30012 0.255257
573379 2013-05-03 18:05:32 Credit 30008 0.256473
572401 2013-05-03 17:59:20 Credit 30001 0.261662
571433 2013-05-03 17:54:17 Credit 30000 0.239688
570477 2013-05-03 17:48:43 Credit 29993 0.241129
569518 2013-05-03 17:35:45 Credit 29986 0.230341
568748 2013-05-03 17:31:58 Debit_ATP 6eLKyhhfcZaQSZgCckCBGPHTM9gM9JL6HX -1.001568
As you can see, total amount between transactions equals 5.00047498 and payout is 4.90047498