After unloading there,i nipped in for a coffee in their cafe,when visiing the loo,the sign on the door said that great care must be taken while opening the door to avoid injuring the person behind the offending door,near fatal death may ensue,due to the high risk of this happening on a daily basis.
Another sign,warned me of certain death if i used the hot hand blower drier,is the loo that unsafe,as i could have got burnt by their blower,the sign said do not put your hands too close.I am surprised the staff were not handing out high viz vests to customers,in case they get knocked down by speeding invalid scooters,while browsing for cheap and nasty Chinese plastic garbage for their garden,imported on a shipping container.
I thought you were going to say they had put a warning sign up AFTER you had used the garden centre toilet 
With the side affects of stomach acid tablets,Omprezole,the fire engine was called out due to a gas leak in the loo. 