I currently work in retail, though I know it's different than supply product for professional use than domestic but i advice any person having issues with their lamps after the years guarantee to do some research into the six year electoral product guarantee as we have previously been able to exchange TVs out of a years guarantee, it's not rail try worked out and you do not receive a refund or replaced 100% free but you can sometimes claim a certain percentage back after the years guarantee If proven not fit for purpose.
Though like I said I am not sure how it works for professional use but it's worth a look into
Hopefully it makes sense.
Honestly the issues I'm reading about CND lamps really puts me off in investing in shellac specially if you have to use their lamps with their gels