Sign in a gym says "We do not make up protein shakes under any circumstances in our blender unless you have brought the protein from us for health and safety reasons. However you can purchase a shaker from us to blend your shake for only £4.99!"
The panel can conceive of a number of good reasons why the sports centre may have a policy in place which declines to mix protein shakes using ingredients provided by customers, but these are not health and safety related. It could simply be a commercial decision to promote their own products or it may be because they are concerned about any possible liability if they do not know the composition of the ingredients they are being asked to mix. The sports centre has now taken down the sign and it is hoped that they will provide customers with a proper explanation for their current policy.