Delet Rows Duplicate In Column A & C And Merge B

i have to clean a worksheet from duplicat rows. The list looks like:

A---------B-----------C
a---------s-----------b
a---------f------------b
a---------s-----------b
a---------e-----------d
a---------d-----------v

Those rows have to be deleted where duplicates exist in column A and C. In our example the first three rows would meet the criteria and two of them have to be deleted. Content of Column B has to be merged with ";" but without duplicates. The result would then look like:

A---------B-----------C
a---------s;f----------b
a---------e-----------d
a---------d-----------v