Simplify the following expression.
$$3\frac{6}{7} - \left\{5\frac{1}{7} - \left(2\frac{3}{7} - 3\overline{\frac{5}{7} - 4}\right)\right\}$$

A

$$\frac{34}{7}$$

B

$$\frac{10}{7}$$

C

$$\frac{20}{7}$$

D

$$\frac{44}{7}$$