Siemens detergent dispenser fault after only 15 years !

After a mere 15 years of faultless service our Seimens E-nr SE26T551GB/04 FD 8607 has developed a fault whereby the detergent dispenser no longer opens during the wash cycle. Manually activating by sliding the small blue tab works and the spring mechanism is in good working order, however this would require someone to remain inside the dishwasher whilst it was working, and whilst I’ve offered good rates of pay no-one has respond to the job advert. Is it likely to be a dispenser fault, a control issue or something else such as an anti-Brexit protest statement ? Thank you in advance.