问题详情

InJanuary2010Amitookoveranoldwarehousewiththeintentionofopeninganartgallery.Asthewarehousehadtobeconverted,Amienteredintotwocontracts,onewithBrytodoallthenecessaryplasteringandonewithCis,whowastodoallthenecessarypainting.BothBryandCisweretobepaid￡5,000.Bothreceivedinitialpaymentsof￡1,000andagreedtohavetheworkcompletedon31March,astheartgalleryhadtobereadyforitsfirstexhibitionon1May.
AttheendofFebruary,BrytoldAmithathewouldnotcompletetheplasteringintimeunlesssheagreedtoincreasehispaymentbyafurther￡1,000.Amiagreedtopaytheincreasedsuminordertoensurethatthejobwasdoneontime.ShethenthoughtitwasonlyfairthatsheshouldincreasetheamountofmoneypromisedtoCisbythesameamount.
However,oncompletionoftheworkontimeAmirefusedtomakeeitheroftheadditionalpaymentstoBryorCis,beyondtheoriginalcontractualprice.
Required:
AdviseBryandCiswhethertheyhaveanyrightsinlawtoenforceAmi’spromisetopaythemanextra￡1,000.
请帮忙给出正确答案和分析，谢谢！