factory srv'c man states 5w fork oil for R*.
With that said some guys run 7w and many run 10wt to firm up fork dampening action a bit to get rid of the mushyness they have with lighetr 5w oil.
But 15w is 3x heavier then yami rec's ,wonder how much of that 3x heavier fork oil they put,like srcewed that up too.
When you have the shop chk out fork cap seals since they used wrong 15w oil have remove the 15w and have then install the correct amount of fork oil in either 7w or 10w,thats up to you.
Most guys get away with out replacing o rings seals on fork caps when doing fork oil change and both yours are leaking?
I am inclined to think they not only used 3x thicker oil then yami rec's but also used way too much fork oil when refilling the fork tubes and the excess oil is being forced past oil seals in form caps.
Tell the shop that the Yami factory srv'c for R* states 18.7oz of oil goe's into each fork tube and that 5W is stock but that you would like either 7w or 10w oil,thats up to you.
If it were my bike i'd go with 10w like already suggested.