Ok...
phillyg15 and
Unclebilbo so 72mg is 7.2% and 52mg is 5.2% is a huge difference strength wise... the highest legal limit in the UK is 75mg or 7.5% ... in vaping terms both are only used diluted down generally pretty significantly. .. but the maths for doing so is substantially different and that 20mg less strength will make a significant difference to the amount you use so yes it should be sent back... but on a more serious note and at the risk of sounding like someones mother here.. if you don't understand the ratios and differences between the two you shouldn't really be going anywhere near mixing until you have learnt these basics... nic is available from china and etc up to 95% that is 950mg ... that stuff will kill you pretty damn easy... but so would 72% or even 52% stuff ... it's why it's not legal to buy here without various poison licences etc... contact poisoning from it is very dangerous. .. this ok doesn't apply to the 52mg 5.2% or 72mg 7.2% stuff... but if you normally vape at even 24mg (2.4%) get the maths wrong by x10 like that and you will be ripping your throat out... and getting a serious nic overdose at the very best...