The Solution is Shoulder Saver: silicone strap cushions.
Shoulder Savers are silicone bra strap cushions that to sit atop your shoulders without slipping to keep straps in place and make your bra more comfortable. They can accommodate straps up to 1 inch (25 mm) wide. Flat and virtually invisible, Shoulder Savers prevent your bra straps from digging into your shoulders and also from slipping down your arm.
Using Shoulder Saver is easy:
1) Place one Shoulder Saver on each shoulder.
2) Open flaps and place bra straps inside.
3) Breathe a sigh of relief because your bra-blem is solved!
Contains: 1 pair
Measures: 3 5/8 x 1 7/8 x 1/8 inches (9.2 x 4.9 x 0.2 cm)
Made in China