Unable to find where transactions sent I sent this transaction and it took a long time to confirm as you can see
023d90420161bbb5f97480d673405d19b79de1c4a7383c8977b62b16926d881c.

Now I have asked the recipient and they have said that I used the wrong address. If that is the case. Where are my bicoin now please?
It is very hard to do a typo in a Bitcoin address, as the address format includes a checksum. Have you checked whether you accidentally sent to a previous business partner? Have you checked whether the address that you sent to matches the address that you were asked to? If the latter is true the error may be on the side of the recipient.

In any case, the coins are now under the control of whomever the recipient address of the transaction belongs to. If


the address is unclaimed: the coins are lost.
the address is claimed by a known entity: you may be able to retrieve them by contacting them.
the address is claimed by an unknown entity: the recipient will do whatever they want.


Try googling the (unique!) respective address to see if someone is asking about receiving an unknown payment. It wouldn't be the first time. ;)