macro to total times for a specific customer

[macdca]

I have a spreadsheet with 5 columns. A is the Customer ID, C has the treatment Date, D has treatment time in minutes (eg 1.6 mins). There can be one or any number of rows per customer per day depending on how many treatments they had that day.

I would like to have one row for each customer totalling up the treatment time for that day, in miuntes

Any ideas?