Tesco sells bondage gear?    Oh, no, sorry, it's a chocolate bar!!!!  (Where do they get these names!)
1 syn per 20 calories.  Trouble is, there are different calorie values given online.  I have seen 100 and 116 per bar.  100 would be 5 syns, 116 almost 6 syns.  You would need to check the information on the package, as they seem to come in different sizes.