As oft repeated on here, but less done in practice:

1. In a CW pile-up only ever send your call-sign ONCE (followed by a listening pause). Never send your call twice.
2. Do NOT repeat your call with the 5NN TU.
3. And even better, trim your 5NN TU to a “5NN dit-dit”! 

73 – Nigel G3TXF