Hopefully i can help..
What model / engine / year - of Vauxhall do you have?
Is this alot of sediment in the tank/floating about?
Hi..there thanks for your responce..
Ok..yes if it a small fine line or small area of sediment then that isnt really all that uncommon to see in some vauxhalls..seen it myself many times..and doesnt normally cause any issues..its when presense of oil/vast amounts of particles/rust is when you have an problem with a component within the coolant system breaking down..ie: pump impeller..If the coolant at present is red and clear then it should be fine and ok to to go about using the car normally..usually with any coolant system it should be tested for strength using a small tester..not sure if your garage did that or not..but usually as per that issue you see can be down the inhibitor in the coolant is breaking down either the age of coolant or two differant coolant types have been mixed at previous time,you will always get some sort of sediment build up in any coolant system over time...the only alternative to this or try to solve it but eventually it will build back up again is to flush the entire system out inc the radiator/heater matrix/coolant system passageways throughout the engine itself/housings and refill with the the proper 50/50 mix of antifreeze/water..but as it stands i dont really see anything to worry about..just keep a monitor on the issue..I do hope this helps..if you need to ask anything else or include anything further then just continue before you rate