Why is it that polish shops in uk refuse to serve british nationals?who do they think they are?

this is a fact that the polish shops selling groceries {which are way cheaper than on sale in british shops} refuse to serve you saying it is for their nationals only, i say british shops and business's should do likewise to them especially as british people are losing their jobs to these people, who stands up for our rights? not the bl00dy labour party thats for sure