Royal Mail executives will be called to Parliament to answer questions about issues with the firm's letter delivery service, the BBC has learned. The Business and Trade Committee had given Royal Mail two weeks to respond to allegations, reported by the BBC, that parcels were being prioritised over letters, resulting in delays to important, time-sensitive mail. While that deadline technically ends on Monday, the BBC understands committee chair Liam Byrne has decided the service is so poor that bosses need to provide answers to MPs. Royal Mail said attending the committee would allow it to discuss the work it was doing to transform the company. It comes after hundreds of people contacted the BBC to express frustration over late deliveries, saying they had missed hospital appointments, and had not received important documents including school certificates and bank statements.…