you have been supplied with standard radiator valves which have a 90 deg bend this allows pipework to come up from floor to a radiator however as you have found towel rails have connection on bottom meaning these valves point towards the wall,to over come this and allow you to connect to pipework from floor you will have to purchase straight radiator valves from plumbing suppliers or believe diy stores do them,if you perchased the valves you have I am sure that although they will not take towel rail back that they would replace with straight valves required
Other option is just to use chrome ball a fix valves of you remove nut and olive from one end it threads straight into towel radiator,pointing down to you connecting pipework (with some ptfe tape and lsx sealing compound
tony...tsp heating
July 2007